Reconstruction of a semiconductor device, such as characteristic adjustment in an analog circuit, rescue of a defective cell in a memory device, etc., are made by mounting in advance a fuse circuit including a plurality of fuses in the semiconductor device and disconnecting the fuses after operational tests, etc. have been made.
The fuses are of the known modes of being disconnected by explosion or sublimation by laser beam irradiation and of being fused by Joule's heat generated by current applied to the fuses, and other modes.
The mode of disconnecting the fuse by laser beam irradiation cannot be made after the package processing and is made in the wafer testing step before the package processing. In the package processing after the semiconductor device has been reconstructed in the wafer state, often the semiconductor chips are strained by the stress of the package resin, and the strain deviates the adjusted device characteristics.
On the other hand, the mode of fusing the fuse can break the fuse in a test after the packaging, and is suitable for trimming requiring high precision for, e.g., adjustment of reference potentials of analog products, etc.
The followings are examples of related: Japanese Laid-open Patent Publication No. 09-069570; and Japanese Laid-open Patent Publication No. 2005-136381.
In the mode of disconnecting the fuse by fusing, current flowed to fuse the fuse and substances around the fuse and then re-solidify the fused areas to electrically disconnect them, and the fuse cannot be sublimated as in disconnecting the fuse by laser beam irradiation. Consequently, depending on structures around the fuse and states of the re-solidified areas, the degree of the electric disconnection is not always sufficient.